The present invention relates to an image generation system, a program, and an information storage medium.
A game system which generates an image viewed from a given viewpoint in an object space, which is a virtual three-dimensional space, has been known. This game system is very popular as a system which allows the experience of so-called virtual reality.
In this game system, it is an important technical subject to generate a more real image in order to improve the sense of virtual reality of the player.
FIG. 13 is illustrative of reflection of light.
Incident light is reflected on a reflection surface at a reflection angle θ′3 which is at the same angle as an incident angle θ3 with respect to the normal direction of the surface, and enters a viewpoint 210.
Taking reflected light rays r1, r2, and r3 which enter the viewpoint 210 after being reflected on the reflection surface at reflection points P1, P2, and P3, respectively, since the reflected light ray r3 reflects light from a light source 220, the reflected light ray r3 is brighter (has higher brightness). Therefore, in the case of generating an image viewed from the viewpoint, the reflection surface (topography, for example) is brighter near the reflection point P3 than near the reflection points P1 and P2.
In order to represent such a reflection of light, it is necessary to compute the reflected light corresponding to the positional relationship between the viewpoint and the light source.
In particular, the processing load of computing the reflected light in real time corresponding to the position of the viewpoint, which is interactively changed by the input of the player, is too heavy for a game system with limited hardware resources.